25566551 has 4 divisors (see below), whose sum is σ = 25581192. Its totient is φ = 25551912.

The previous prime is 25566523. The next prime is 25566559. The reversal of 25566551 is 15566552.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 25566551 - 2¹⁸ = 25304407 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25566559) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4280 + ... + 8333.

It is an arithmetic number, because the mean of its divisors is an integer number (6395298).

Almost surely, 2^25566551 is an apocalyptic number.

25566551 is a deficient number, since it is larger than the sum of its proper divisors (14641).

25566551 is a wasteful number, since it uses less digits than its factorization.

25566551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14640.

The product of its digits is 45000, while the sum is 35.

The square root of 25566551 is about 5056.3377062851. The cubic root of 25566551 is about 294.5941023098.

Subtracting from 25566551 its reverse (15566552), we obtain a palindrome (9999999).

The spelling of 25566551 in words is "twenty-five million, five hundred sixty-six thousand, five hundred fifty-one".